Air Conditioning in a room with an open fireplace: Pointless?

desperaterobots · November 2008

Calling handypersons!

I've moved into a rented house and my bedroom has a fireplace. It's also heading into summer so I've set up my air-conditioner. And it's occurred to me that all that refridgerated air will probably wind up going up the chimney.

So I need to cover this thing over. I tried with plastic and the thing acted like a diaphragm, a noisy one that woke me up all the time. Can you buy fireplace covers? Would a piece of wood sealed with something like blu-tac or gaffer/cloth tape work? I've tried googling for help on this and I've only come up with renovation ideas for bricking over or tiling a fireplace.

Possibly a long shot: has anyone done this?

Willeth · November 2008

Shove some scrunched-up newspaper in there so it's wedged. You'll still get a lot of transfer but no nearly as much as an open passage and it's not like it's expensive if it fails.

RUNN1NGMAN · November 2008

Doesn't the chimney have a damper that you can close?

Cauld · November 2008

my family always shoved up pillows (old pillows we no longer used). That worked well. They'll come out covered in soot though.

EggyToast · November 2008

Cold air doesn't rise; it falls. Similarly, the chimney likely has a flue that is closed.

Scrublet · November 2008

Generally chimney's won't affect your cooling in the summer. They will mostly only affect your heating in the winter.

ProPatriaMori · November 2008

The chimney should indeed have a bit that's quite sealed and the cold air should be heading toward the floor, not the sky.

If anything, an unblocked chimney should help warm air escape as it's displaced by colder air.

MrMonroe · November 2008

Ask the owner where the flue can be found so you can close it.

Of course, air in chimneys is pretty much static unless hot air enters them, which makes the air flow much more rapidly. Cold air at the bottom won't create that effect, so the heat increase would be entirely through convection; i.e. probably about the same as the cracks in your windows.

desperaterobots · November 2008

Hmm. This is a really old house, I'm not sure the chimneys can be closed, but I'll ask the landlord. Pillows sound like a great idea though. And I thought the same regarding the 'hot air will go up' thing, but having that plastic over the fireplace, well, it sounded like a sail on a yacht catching a gust of air half the time, so I'm skeptical that the low-lying cool air won't just be vacuumed out of the house if the pressure outside is low...

Kivutar · December 2008

Well, just with a quick google search, I can see that the chimney damper has been in use for at least 200 years.

Odds are there's a way to close yours without stuffing it with pillows.

LewieP's Mummy · December 2008

1. Chimneys are designed to suck air out of a room - as the wind blows across the chimney pot, air pressure in the chimney changes and air from the room is sucked up into the atmosphere.

2. Hot air rises, but will rise to the ceiling, as that is higher than the fireplace opening. Some will go up the chimney, but not much.

3. Block it off, but remember you have before you light a fire in the winter! Pillows work, as does edging the inside of the fireplace opening with double sided tape and placing a piece of hardboard (on which you have painted a pretty pictrure) inside the opening, pressed against the double sided tape.

Oh to live somewhere warm enough to need AC!

desperaterobots · December 2008

Yay LewieP's Mummy! That's how I figured it worked since the plastic I put over the cover was constantly sucking in and out, especially in the wind. I might stuff a pillow or two up there and get a piece of cardboard (it's not a square opening and I dont have any wood-cutting tools) and tape all around the edges. There's no dampners unfortunately.

Thanks guys.

desperaterobots · December 2008

Thanks, spambot!

Derpan · December 2008

1. Using a tape measure the dimensions of the fireplace entrance

2. Go to local hardware store and buy a piece of insulation foam ( $5.00 or so )

3. Cut foam to dimensions previously measured but add 1-2 cm to the total height and width.

4. Wedge foam into fireplace entrance and it will form a snug barrier that will not shift due to changes in pressure.

Make sure the flue is closed and that you have no side flues that are open.

If you want to be gung-ho about it, measure another piece of foam from he same piece and wedge it on the horizontal plane at the top of the inside of the fireplace, making a dual layered barrier.

Here is a nifty guide I made to help

desperaterobots · December 2008

Hahaha. Wow. Great advice and an incomprehensible cartoon guide!

Penny Arcade

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Air Conditioning in a room with an open fireplace: Pointless?

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